Floaters and posterior vitreous detachment
By Dr Neeraj Jain, MD (Ophthalmology), DNB, MNAMS
What are floaters?
As the name suggests, floaters are little ‘cobwebs’ or specks that float about in your field of vision. They are small, dark, shadowy shapes that look like dark spots, thread-like strands, or squiggly lines. They move as your eyes move and seem to dart away when you try to look at them directly. They do not follow your eye movements precisely, and usually drift away when your eyes stop moving.
Most people have floaters. They are usually not noticed until they become more frequent. Floaters can become apparent when looking at something bright, such as white paper or the blue sky.
What causes floaters?
The vitreous is a transparent gel-like substance that fills about 80 per cent of the eye volume (please refer to the picture). It helps the eye to maintain its round shape.
Due to old age or inflammation, some of the contents of this gel are lost and it slowly shrinks. This process may lead to development of liquid pockets which ultimately causes the collapse of the vitreous gel.
As the vitreous shrinks, it becomes somewhat ‘stringy’; and the strands can cast tiny shadows on the retina. These are called floaters.
In most cases, floaters are part of the aging process. However, there are more serious causes of floaters, including infection, inflammation (uveitis), haemorrhage, retinal tears, and injury to the eye. Over time these floaters tend to ‘sink’ down to the bottom of the eye, becoming less bothersome.
Who is at risk for floaters?
Floaters develop as we get older and are common in people who are very nearsighted, have diabetes, had trauma to the eye or who have had cataract surgery.
What is a vitreous detachment?
Generally, the vitreous gel adheres to the retina at multiple places and remains in position due to these tight ‘attachments.’ The degenerative processes in the vitreous forms lots of liquid pockets inside the gel substance. The normal movements of the eye can no longer hold the whole vitreous together and it starts moving at a different rate than the eye movements. Finally, this leads to separation of the vitreous from its retinal attachment sites. Once the vitreous is totally detached from retina, it becomes a free moving body inside the eye and finally sinks to the bottom.
Although a vitreous detachment does not threaten sight, once in a while, some of the vitreous fibres pull so hard on the retina that they create a hole or lead to a retinal detachment. Both the mentioned conditions (retinal hole and retinal detachment) are sight-threatening and should be treated immediately.
What are the symptoms
of a vitreous detachment?
Usually the symptoms affect one eye and over years it may involve the other.
Floaters − seen as spots, dots, circles, clouds, or spider webs ‘float’ in front of the eyes and move with the eye.
* Flashes − Visual light without any source, due to the vitreous pulling on the retina
* Sudden loss of vision − due to haemorrhage or retinal detachment.
How it is diagnosed?
It can be diagnosed by an eye examination, which includes:
* Dilated eye examination to evaluate the vitreous, retina with the help of indirect ophthalmoscopy and diagnostic lenses.
* Eye ultrasonography, when the cornea, lens or vitreous is not clear.
Floaters and
retinal detachment
Floaters sometimes may be the only warning symptom of retinal detachment. For a common man it’s very difficult to distinguish the origin of floaters. So in general, all floaters are considered dangerous unless proven otherwise.
In general, vitreous detachment causes floaters. Retinal detachment is an unusual sequel to the ‘chain reaction’ of vitreous degeneration-vitreous detachment- retinal hole – retinal detachment.
The only way to diagnose the problem is a comprehensive dilated eye examination. If the vitreous detachment has led to a retinal hole or detached retina, early treatment can prevent loss of vision.
What is the treatment?
For people who have floaters that are simply annoying, no treatment is recommended. Over time, with the collapse of the vitreous body, all floaters tend to disappear. No doubt it’s a slow process and takes years.
On rare occasions, floaters can be so dense and numerous that they significantly affect vision. In these cases, a vitrectomy (a surgical procedure that removes floaters from the vitreous) may be needed. This operation carries significant risk to vision because of possible complications. Most eye surgeons are reluctant to recommend this surgery unless the floaters seriously interfere with vision.
What is the prognosis?
Often being a normal part of aging, posterior vitreous detachment does not require specific treatment. So in general, they portend a good prognosis.
However, a sudden increase in floaters, accompanied by light flashes or peripheral (side) vision loss, could indicate a retinal detachment.
Those who experience a sudden increase in floaters, flashes of light in peripheral vision, or a loss of peripheral vision should have an eye care professional examine their eyes as soon as possible.
